Error detection method for memory device

ABSTRACT

The disclosure provides an error detection method for a memory device, wherein the memory device comprises a plurality of memory blocks, and each of the memory blocks has a plurality of word lines connected to a plurality of memory cells, the error detection method comprises the following steps. Performing a plurality of times of programming operations on the memory cells connected to each of the word lines to program the memory cells as a plurality of programming-level states. Performing a plurality of times of verifying operations on the memory cells to verify the programming-level states respectively. When the number of verifications of the verifying operations for one of the programming-level states is greater than an upper limit number corresponding to the one of the programming-level states, marking the word line as an error word line.

TECHNICAL FIELD

The disclosure relates to an error detection method for a semiconductordevice, particularly relates to a method for detecting abnormalprogramming operations of a memory device.

BACKGROUND

Uncertainties in the manufacturing process may cause defects in thehardware components of the memory device. Furthermore, during the use ofthe memory device, after times of programming/erasing cycles areperformed, the memory device may be also gradually worn-out. Eitherdefects during the manufacturing process or wearing-out during use,errors in stored data of the memory device may be induced.

For a worst case, abnormality exists in the memory device and causeserrors in programmed data written in the memory device. But, some ofprogramming-level states of the memory device still pass verification,hence programmed data is misjudged as being correct. Then, programmeddata is read, however, errors in programmed data cannot be corrected andrecovered by an error correction mechanism (e.g., by an error correctioncode (ECC)).

In view of the above technical problems, skilled ones of relatedindustries in this technical field are devoted to detect abnormalconditions of memory devices at an earlier stage, and to isolate memoryblocks (or word lines) detected as abnormal to protect programmed data.

SUMMARY

According to one aspect of the disclosure, an error detection method fora memory device is provided. Wherein the memory device comprises aplurality of memory blocks, and each of the memory blocks has aplurality of word lines connected to a plurality of memory cells, theerror detection method comprises the following steps. Performing aplurality of times of programming operations on the memory cellsconnected to each of the word lines to program the memory cells as aplurality of programming-level states. Performing a plurality of timesof verifying operations on the memory cells to verify theprogramming-level states respectively. When the number of verificationsof the verifying operations for one of the programming-level states isgreater than an upper limit number corresponding to the one of theprogramming-level states, marking the word line as an error word line.

According to another aspect of the disclosure, an error detection methodfor a memory device is provided. Wherein the memory device comprises aplurality of memory blocks, and each of the memory blocks has aplurality of word lines connected to a plurality of memory cells, theerror detection method comprises the following steps. Performing aplurality of times of programming operations on the memory cellsconnected to each of the word lines to program the memory cells as aplurality of programming-level states. Performing a plurality of timesof verifying operations on the memory cells to verify theprogramming-level states respectively. When the amount of memory cellspassing verification for one of the programming-level states is lessthan a lower limit amount, marking the word line as an error word line.

According to still another aspect of the disclosure, an error detectionmethod for a memory device is provided. Wherein the memory devicecomprises a plurality of memory blocks, and the memory blocks compriseat least a first memory block and a second memory block, the errordetection method comprises the following steps. Performing a pluralityof times of programming operations on a plurality of memory cells of thefirst memory block and a plurality of memory cells of the second memoryblock to program the memory cells of the first memory block and thememory cells of the second memory block as a plurality ofprogramming-level states. Performing a plurality of times of verifyingoperations on the memory cells of the first memory block and the memorycells of the second memory block to verify the programming-level statesrespectively. When a difference value between the number ofverifications of the verifying operations for the same programming-levelstate of the first memory block and the second memory block is greaterthan a standard number, marking the first memory block and/or the secondmemory block as error memory block(s).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic diagram of a memory device to which the errordetection method of an embodiment of the disclosure is applied.

FIG. 1B is a circuit diagram of the memory block of the memory device inFIG. 1A.

FIG. 2 is a schematic diagram of the threshold voltage distribution ofdifferent programming-level states after the memory device is performedwith programming operations.

FIGS. 3A to 3C are schematic diagrams of programming operations andverifying operations in one of the programming-level states.

FIG. 4 is a schematic diagram illustrating executing several times ofprogramming loops to make one of the programming-level states pass theverification.

FIG. 5 is a schematic diagram illustrating the verification referencevoltages and the number of verifications for different programming-levelstates.

FIG. 6 is a schematic diagram illustrating reading a programmed data ofthe error word line and writing it to another word line, in the errordetection method of an embodiment of the disclosure.

FIG. 7 is a schematic diagram illustrating reading a programmed data ofan error memory block and writing it to another memory block, in theerror detection method of an embodiment of the disclosure.

FIGS. 8A to 8C are schematic diagrams illustrating analyzing the amountof memory cells passing verification, in the error detection method ofanother embodiment of the disclosure.

FIG. 9 is a schematic diagram illustrating comparing the number ofverifications of two memory blocks, in the error detection method ofstill another embodiment of the disclosure.

FIG. 10 is a flow diagram of the error detection method of an embodimentof the disclosure.

FIG. 11 is a flow diagram of the error detection method of anotherembodiment of the disclosure.

FIG. 12 is a flow diagram of the error detection method of still anotherembodiment of the disclosure.

In the following detailed description, for purposes of explanation,numerous specific details are set forth in order to provide a thoroughunderstanding of the disclosed embodiments. It will be apparent,however, that one or more embodiments may be practiced without thesespecific details. In other instances, well-known structures and devicesare schematically illustrated in order to simplify the drawing.

DETAILED DESCRIPTION

FIG. 1A is a schematic diagram of a memory device 1000 to which theerror detection method of an embodiment of the disclosure is applied,and FIG. 1B is a circuit diagram of the memory block BLK1 of the memorydevice 1000 in FIG. 1A. Please refer to FIGS. 1A and 1B, the memorydevice 1000 includes a plurality of memory blocks BLK1˜BLKn, and each ofthe memory blocks BLK1˜BLKn has a plurality of word lines. For example,the memory block BLK1 has word lines WL1-1 to WL1-m.

Furthermore, each of the word lines WL1-1˜WL1-m is connected to aplurality of memory cells. For example, the word line WL1-1 is connectedto a plurality of memory cells 100, and the word line WL1-2 is connectedto a plurality of memory cells 200. In this embodiment, each of thememory cells 100 and 200 may refer to, for example, a multi-level cell,which can store multi-bit data.

FIG. 2 is a schematic diagram of the threshold voltage distribution ofdifferent programming-level states A˜G after the memory device 1000 isperformed with programming operations. Please refer to FIG. 2 (also seeFIG. 1B by reference), taking the word line WL1-1 of the memory blockBLK1 of the memory device 1000 as an example, all the memory cells 100connected to the word line WL1-1 are in the erase state, i.e.,“S0-state”, hereinafter referred to as erase state S0. The erase stateS0 may correspond to three-bit data “1, 1, 1”. In one example, thememory device 1000 may refer to, e.g., a floating gate memory or acharge trapping memory. When a programming operation is performed on thememory cells 100 of the memory device 1000, a plurality of programingpulses can be applied to the control gates of the memory cells 100, soas to make the amount of charges in the floating gates of the memorycells 100 change. Therefore, to increase the threshold voltage Vt of thememory cells 100 to different levels of voltage distribution, hence thememory cells 100 may be in different programming-level states. In otherexamples, the memory device 1000 may also refer to other types ofnon-volatile memory. After a plurality of programming pulses areapplied, threshold voltage Vt of memory cells 100 of memory device 1000of types of non-volatile memory may be enhanced to differentprogramming-level states. Taking the memory cells 100 as triple levelcells (TLC) as an example, after a plurality of programming operationsare performed, the memory cells 100 can be programmed as sevenprogramming-level states. For example, a part of the memory cells 100,which are memory cells 101, may be programmed as a lower level of“A-state” (also referred to as “A-level”, hereinafter referred to as“programming-level state A”). In addition, another part of the memorycells 100, which are memory cells 102, may be programmed as a next lowerlevel of “B-state” (also referred to as “B-level”, hereinafter referredto as “programming-level state B”). Likewise, still another part of thememory cells 100, which are memory cells 107, may be programmed as ahigher-level of “G-state” (also referred to as “G-level”, hereinafterreferred to as “programming-level state G”).

FIGS. 3A to 3C are schematic diagrams of programming operations andverifying operations in programming-level state A. Please refer to FIG.3A first, the error detection method of this embodiment can be executedfrom a lower level of programming-level state A. A part of the memorycells 101 in the memory cells 100 is to be programmed asprogramming-level state A, and these memory cells 101 are originally inerased state S0.

After performing one time of programming operation on the memory cells101 to apply one time of programming pulse, the threshold voltage Vt ofthe memory cells 101 can be increased. Furthermore, one time ofverifying operation is performed to determine whether the thresholdvoltage Vt of the memory cells 101 is greater than a verificationreference voltage Vv-A. Applying one time of programming pulse andperforming one time of verifying operation, may be referred to as onetime of “programming loop”.

After performing several times of programming loops (for example, eighttimes of programming loops), the memory cells 101 are enhanced fromerased state S0 to a temporary (or intermediate) level state A8. Herein,for level state A8, the number of times of executing programming loops,which is referred to as “NL”, is “8” (i.e., number of programming loops“NL”=8). Furthermore, the number of times of executing verifyingoperations, which is referred to as “NV”, is also “8” (i.e., number ofverifications “NV”=8). When the memory cells 101 are in temporary levelstate A8, threshold voltage Vt of the memory cells 101 b is greater thanthe verification reference voltage Vv-A and hence pass verification.However, threshold voltage Vt of the other part of the memory cells 101,said, the memory cells 101 a, is still less than the verificationreference voltage Vv-A and not passing verification yet. Therefore, moretimes of programming loops need to be performed to further increasethreshold voltage Vt of the memory cells 101.

Next, referring to FIG. 3B, after the ninth times of programming loop isexecuted (meanwhile, the number of programming loops NL is “9”, and thenumber of verifications NV is “9”), the memory cells 101 are enhanced tolevel state A9. When in the level state A9, the threshold voltages Vt ofall the memory cells 101 are greater than the verification referencevoltage Vv-A and hence pass the verification for all, and programming ofthe memory cells 101 is completed. The level state A9 may refer to thetarget programming-level state A (i.e., “A-state” shown in FIG. 3B).

In the error detection method of the disclosure, an corresponding upperlimit number Nmax may be respectively set for corresponding one ofprogramming-level states A˜G, such as, an upper limit number Nmax-A maybe set for programming-level state A. Furthermore, number ofverifications NV in the programming-level state A is compared to checkwhether it is greater than the upper limit number Nmax-A correspondingto programming-level state A. (In another example, it may also checkwhether the number of programmed loops NL corresponding toprogramming-level state A is greater than the upper limit number Nmax-Acorresponding to programming-level state A). When the number ofverifications NV is greater than the upper limit number Nmax-A, (i.e.,number of verifications is too many), it indicates that programmingoperation of the programming-level state A is abnormal, and memory cells101 and/or word line WL1-1 (which is connected to the memory cells 101)may be determined as having defects in hardware components and henceoperates abnormally.

For example, the word line WL1-1 and its adjacent word line may beshort-circuited, or the word line WL1-1 and the channel region may beshort-circuited. In this embodiment, the upper limit number Nmax-Acorresponding to programming-level state A is set as “10”, and number ofverifications NV of “9” for programming-level state A is less than theupper limit number Nmax-A of “10”, indicating that programmingoperations of programming-level state A are normally performed, and itmay be determined that the word line WL1-1, which is connected to thememory cells 101, also operates normally (i.e., determining that wordline WL1-1 is a “healthy” word line).

However, as shown in FIG. 3C, if the word line WL1-1 operatesabnormally, it may cause a larger amounts of defective memory cells 101c. The defective memory cell 101 c may be referred to as “slow” bits or“tail” bits. The threshold voltage Vt of these memory cells 101 c isstill lower than the verification reference voltage Vv-A and cannot passverification, hence, more programming loops need to be performed.

Next, please refer to FIG. 4 , which illustrates executing several timesof programming loops to make the programming-level state A pass theverification. If the word line WL1-1 operates abnormally, for example,it is necessary to perform eleven times of programming loops (number ofprogramming loops NL is “11” and number of verifications NV is “11”) tomake all the memory cells 101 pass the verification. Herein, the numberof verifications NV of “11” in the programming-level state A (i.e.,“A-state” shown in FIG. 4 ) is greater than the upper limit numberNmax-A of “10”, indicating too many number of verifications. Therefore,it may be determined that programming operations for theprogramming-level state A may be failed or abnormal, and an informationof “status of abnormal programming operation” is reported. It may bealso determined that the word line WL1-1 connected to the memory cells101 may have defect in hardware component and cause abnormal operation,and the word line WL1-1 is marked as an error word line or “risky” wordline.

FIG. 5 is a schematic diagram illustrating the verification referencevoltages Vv-A˜Vv-G and the number of verifications NV for differentprogramming-level states A˜G. Referring to FIG. 5 , the memory cells 100may be programmed as seven programming-level states A˜G respectively,and verifying operations may be performed respectively according to theverification reference voltages Vv-A˜Vv-G. Number of verifications NVfor each of the programming-level states A˜G may be respectivelycompared with the corresponding upper limit number Nmax, so as to checkwhether number of verifications NV is greater than the upper limitnumber Nmax. Different programming-level states may have differentvalues of upper limit number Nmax, such as, upper limit number Nmax-A of“10” may correspond to programming-level states A, upper limit numberNmax-B of “9” may correspond to programming-level states B, upper limitnumber Nmax-C of “8” may correspond to programming-level states C, . . ., and upper limit number Nmax-E of “11” may correspond toprogramming-level states E, . . . , etc. When number of verifications NVof any one of programming-level states A˜G is greater than the upperlimit number Nmax, it may be determined that the word line WL1-1, whichis connected to the memory cells 100, may have defect in hardwarecomponent and result in abnormal operation, and the word line WL1-1 ismarked as an error word line. For example, number of verifications NV of“11” for programming-level state A is greater than the upper limitnumber Nmax-A of “10” corresponding to programming-level state A, andnumber of verifications NV of “12” for programming-level state E is alsogreater than the upper limit number Nmax of “11” corresponding toprogramming-level state E, it may be determined that word line WL1-1connected to the memory cells 100 may operate abnormally.

In an example, when number of verifications NV for a lower-level ofprogramming-level state is greater than the upper limit number Nmax,programming operation for the memory cells 100 of the word line WL1-1may be stopped or terminated immediately, and no more programmingoperations will be performed for higher-level programming-level states.For example, if number of verifications NV of “11” for programming-levelstate A is greater than the upper limit number Nmax-A of “10”corresponding to programming-level state A, then programming operationwill not be performed to higher-level of programming-level states B˜G.

In another example, verification result of the previousprogramming-level state and verification result of the currentprogramming-level state can be used to determine whether programmingoperations are abnormal. For example, if the previous programming-levelstate A has passed verification, and number of verifications NV of “9”for the current programming-level state B has reached the upper limitnumber Nmax-B of “9” corresponding to programming-level state B butstill fails the verification, it may be determined that programmingoperations are abnormal.

FIG. 6 is a schematic diagram illustrating reading a programmed data ofthe error word line and writing it to another word line, in the errordetection method of an embodiment of the disclosure. Please refer toFIG. 6 , when number of verifications NV for any one of theprogramming-level states A˜G is greater than the upper limit numberNmax, the word line WL1-1 may be marked as an error word line, and aprogrammed data PGM_data1 in the memory cells 100 connected to the errorword line WL1 can be read. Furthermore, the programmed data PGM_data1 iswritten into another word line. For example, the word line WL1-2operates normally, and programmed data PGM_data1 may be written into thememory cells 200 connected to the word line WL1-2, so as to preserveprogrammed data PGM_data1. It may achieve effects of protecting correctdata with data recovery.

FIG. 7 is a schematic diagram illustrating reading a programmed data ofan error memory block and writing it to another memory block, in theerror detection method of an embodiment of the disclosure. Please referto FIG. 7 , the memory block BLK1 to which the error word line WL1-1belongs may be marked as an error memory block, and programmingoperations for memory cells connected to all word lines WL1-1˜WL1-m inthe error memory block BLK1 may be stopped. Furthermore, a programmeddata PGM_data2 in the memory cells of the error memory block BLK1 may beread, and the programmed data PGM_data2 may be written into anothermemory block. For example, if the memory block BLK2 operates normally,programmed data PGM_data2 is written into the memory block BLK2 topreserve programmed data PGM_data2.

FIGS. 8A to 8C are schematic diagrams illustrating analyzing the amountof memory cells passing verification, in the error detection method ofanother embodiment of the disclosure. In the embodiment shown in FIGS.8A to 8C, programming operations may be determined as abnormal accordingto the amount of memory cells having passed verification. Please referto FIG. 8A (also see FIG. 1B by reference), a predetermined number “Nd”of programming loops for the memory cells 101 in the programming-levelstate A can be set as “6”. When the memory cells 101 are executed withsix times of programming loops (i.e., number of programming loops NL is“6”) has reached the predetermined number Nd of “6”, amount of memorycells 101 b which have passed verification (i.e., threshold voltage Vtis greater than the verification reference voltage Vv-A) may beanalyzed. When amount of memory cells 101 b is less than or equal to alower limit amount Cmin, it may be determined that programmingoperations for the memory cells 101 have failed, and determined that theword line WL1-1 connected to the memory cells 101 operates abnormally.Furthermore, the word line WL1-1 is marked as a wrong word line.

In an example (similar to the example in FIG. 6 ), when the amount ofmemory cells 101 b (which pass verification) is less than or equal tothe lower limit amount Cmin, programming operations for all memory cells100 connected to the wrong word line WL1-1 may be terminated. Inaddition, programmed data PGM_data1 in the memory cells 100 connected tothe error word line WL1-1 may be read, and programmed data PGM_data1 maybe written into memory cells 200 of another word line which operatesnormally (for example, word line WL1-2), so that programmed dataPGM_data1 may be preserved.

In another example (similar to the example in FIG. 7 , when the amountof memory cells 101 b (which has passed verification) is less than orequal to the lower limit amount Cmin, the memory block BLK1 to which theerror word line WL1-1 belongs may be marked as an error memory block,and programming operations for memory cells connected to all the wordlines of the error memory block BLK1 may be terminated. Furthermore,programmed data PGM_data2 in the memory cells of the error memory blockBLK1 may be read, and programmed data PGM_data2 may be written intomemory cells of another normally operated memory block (for example, thememory block BLK2). In this manner, programmed data PGM_data2 may bepreserved.

In other examples, different predetermined numbers Nd for programmingloops and different lower limit amounts Cmin may be set for differentprogramming-level states A˜G respectively. For example, predeterminednumbers Nd of programming loops for programming-level states B and D are“5” and “7” respectively. As shown in FIG. 8B, when number ofprogramming loops NL of “5” for the programming-level state B hasreached the predetermined number Nd of “5”, the amount of memory cells102 b (which have passed verification) in the memory cell 102 isdetermined whether being less than the lower limit amount Cmin of“25000”. On the other hand, as shown in FIG. 8C, when number ofprogramming loops NL of “7” for the programming-level state D hasreached the predetermined number Nd of “7”, the amount of memory cells104 b (which have passed verification) in the memory cell 104 isdetermined whether being less than the lower limit amount Cmin of“45000”.

In addition, the predetermined number Nd of programming loops may beadjusted according to status of the memory device 1000. For example,when the memory device 1000 has been used for a long time and in the endof life, the predetermined number Nd of programming loops may be set asa smaller value.

Compared with the error detection method of FIGS. 3A-3C and FIG. 4 , theerror detection method of FIGS. 8A-8C may detect abnormal programmingoperations earlier. Taking programming-level state A as an example, inthe example of FIG. 8A, when the number of programming loops NL reachesthe predetermined number Nd of “6”, it may be immediately checkedwhether the amount of memory cells 101 b (which pass the verification)is too small. However, in the example shown in FIG. 3B, before checkingwhether the number of verifications NV is too large, it is necessary towait for all the memory cells 101 to pass verification. In other words,when number of programming loops NL reaches “6” the scheme of FIG. 8Amay do checking earlier. However, the scheme of FIG. 3B may check later,until more programming loops (e.g., number of programming loops NL of“9”) are executed.

FIG. 9 is a schematic diagram illustrating comparing the number ofverifications of two memory blocks, in the error detection method ofstill another embodiment of the disclosure. Please refer to FIG. 9 ,programming operations may be performed on the memory blocks BLK1˜BLKnin the memory device 1000 respectively, and verifying operations may beperformed to verify the programming-level states, and may furtheranalyze number of verifications for the same programming-level state ofthe two memory blocks. For example, to analyze number of verifications“NV1” for the programming-level state A of the memory block BLK1 (e.g.,NV1=10), and analyze number of verifications “NV2” for the sameprogramming-level state A of the memory block BLK2 (e.g., NV2=13). Inaddition, a difference value “df_NV” between number of verifications NV1and number of verifications NV2 is calculated, and difference valuedf_NV equals “3”. Furthermore, a standard number “Ns” is set (e.g.,setting Ns as “2”).

When difference value df_NV of “3” is greater than standard number Ns of“2”, it may be determined that at least one of memory blocks BLK1 andBLK2 has abnormal programming operations. In one example, since numberof verifications NV2 of “13” of memory block BLk2 is greater than numberof verifications NV1 of “10” of memory block BLk1, it may be determinedthat memory block BLK2 (with greater number of verifications) isabnormal, and memory block BLK2 may be marked as an error memory block.In another example, memory block BLK1 and memory block BLK2 may bothhave abnormal programming operations, then memory blocks BLK1 and BLK2are both marked as error memory blocks.

Programming operations for the memory cells in the error memory blockBLK2 (the memory cells are not shown in FIG. 9 ) may be terminated, anda programmed data PGM_data3 in the memory cells of the error memoryblock BLK2 may be read. Furthermore, the programmed data PGM_data3 maybe written into memory cells of another memory block. For example, thememory block BLK4 well functions, and programmed data PGM_data3 may bewritten into the memory block BLK4 to preserve programmed dataPGM_data3. In another example, when memory blocks BLK1 and BLK2 are bothmarked as error memory blocks, programming operations for the memorycells in the error memory blocks BLK1 and BLK2 may be terminated.

FIG. 10 is a flow diagram of the error detection method of an embodimentof the disclosure, which corresponds to the embodiment illustrated inFIGS. 3A-3C and FIGS. 4-7 . Referring to FIG. 10 , in step S110,programming operations are performed to the memory cells 100 (takingtriple level cells as an example) to program as the programming-levelstates A˜G, and verifying operations are performed to verify theprogramming-level states respectively A˜G. Then, in step S120, it isdetermined whether number of verifications NV of anyone of theprogramming-level states A˜G is greater than the respective upper limitnumber Nmax corresponding to programming-level states A˜G. For example,determining whether number of verifications NV of programming-levelstate A is greater than the upper limit number Nmax-A corresponding toprogramming-level state A, and determining whether number ofverifications NV of programming-level state B is greater than the upperlimit number Nmax-B corresponding to programming-level state B, etc.When number of verifications NV for programming-level states A˜G is lessthan or equal to the respective upper limit number Nmax corresponding toprogramming-level state A˜G, it may be determined that programmingoperations are normal, and then executing step S130: continue to performthe programming operations to the memory cells 100.

On the other hand, when number of verifications NV for programming-levelstates A˜G is greater than the respective upper limit number Nmaxcorresponding to programming-level state A˜G in step S120, it may bedetermined that the programming operations are abnormal, then executingstep S140: terminating programming operations of the word line WL1-1connected to the memory cells 100, and the word line WL1-1 is marked asan error word line. Then, step S150 is executed to read programmed dataof the error word line WL1-1 and write it to another word line.

Alternatively, when number of verifications NV is greater than the upperlimit number Nmax in step S120, may also execute step S160: terminatingprogramming operations of the memory block BLK1 (to which the word lineWL1-1 belongs), and marking the memory block BLK1 as an error memoryblock. Then, step S170 is executed to read programmed data in the errormemory block BLK1 and write it to another normally operating memoryblock.

FIG. 11 is a flow diagram of the error detection method of anotherembodiment of the disclosure, which corresponds to the embodimentillustrated in FIGS. 8A-8C. The method flow in FIG. 11 is substantiallythe same as the method flow in FIG. 10 , the difference lies in stepS220 of FIG. 11 . In step S220, it is determined whether amount ofmemory cells passing verification in one of programming-level states Ato G is less than the lower limit amount Cmin. If it is greater than orequal to the lower limit amount Cmin, it may be determined thatprogramming operations are normal, and step S230 is executed. On theother hand, if it is less than the lower limit amount Cmin, it may bedetermined that programming operations are abnormal, and step S240 isexecuted.

FIG. 12 is a flow diagram of the error detection method of still anotherembodiment of the disclosure, which corresponds to the embodimentillustrated in FIG. 9 . Referring to FIG. 12 , in step S310, programmingoperations are performed to the memory cells of the first memory blockBLK1 and the second memory block BLK2 of the memory device 1000, so thatmemory cells of the first memory block BLK1 and the second memory blockBLK1 have a plurality of programming-level states A˜G (take the triplelevel cells as an example). In addition, verifying operations areperformed on the first memory block BLK1 and the second memory blockBLK2 to verify the programming-level states A˜G respectively.

Then, in step S320, it is determined whether difference value df_NVbetween number of verifications NV1 of the first memory block BLK1 andnumber of verifications NV2 of the second memory block BLK2 for the sameprogramming-level state of the (for example, the same programming-levelstate A) is greater than the standard number Ns. When the differencevalue df_NV is less than or equal to the standard number Ns, it may bedetermined programming operations are normal, then executing step S330:programming operations are continued for the first memory block BLK1 andthe second memory block BLK2.

On the other hand, when the difference value df_NV is greater than thestandard number Ns, it may be determined that programming operations areabnormal, then executing step S340: the memory block with a largernumber of verifications (for example, the second memory block BLK2) ismarked as the error memory block, and programming operations of theerror memory block BLK2 are terminated. In another example, when firstmemory block BLK1 and second memory block BLK2 may both have abnormalprogramming operations, then first memory block BLK1 and second memoryblock BLK2 are both marked as error memory blocks and their programmingoperations are terminated.

Then, executing step S350: reading programmed data in the error memoryblock BLK2, and write programmed data into another normally operatingmemory block.

According to the above embodiments, the error detection method for thememory device 1000 of the disclosure may analyze and check whethernumber of verifications NV or number of programming loops NL fordifferent programming-level states is too many (exceeding respectiveupper limit number Nmax corresponding to programming-level states), soas to determine whether programming operations are abnormal anddetermine whether word line is abnormal. It may also analyze and checkwhether the amount of memory cells passing verification in a particularprogramming-level state is too small (less than lower limit amountCmin), or analyze and check difference value between number ofverifications for two memory blocks (or check difference value betweennumber of programing loops) is too large (exceeding standard number Ns).Solution provided in the disclosure may determine abnormal programmingoperations in early stage and immediately terminate programmingoperations. In addition, when it is determined that the word line ormemory block is abnormal, programmed data that has been written in theword line or memory block can be read, and programmed data may bewritten to other normal word line or normal memory block so as topreserve or recover programmed data.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the disclosed embodiments.It is intended that the specification and examples be considered asexemplary only, with a true scope of the disclosure being indicated bythe following claims and their equivalents.

What is claimed is:
 1. An error detection method for a memory device,wherein the memory device comprises a plurality of memory blocks, andeach of the memory blocks has a plurality of word lines connected to aplurality of memory cells, the error detection method comprises thefollowing steps: performing a plurality of times of programmingoperations on the memory cells connected to each of the word lines toprogram the memory cells as a plurality of programming-level states:performing a plurality of times of verifying operations on the memorycells to verify the programming-level states respectively; and when thenumber of verifications of the verifying operations for one of theprogramming-level states is greater than an upper limit numbercorresponding to the one of the programming-level states, marking theword line as an error word line.
 2. The error detection method accordingto claim 1, further comprises the following step: terminating theprogramming operations of the memory cells connected to the error wordline.
 3. The error detection method according to claim 2, furthercomprises the following step: reading a programmed data in the memorycells connected to the error word line, and writing the programmed datainto a plurality of memory cells connected to another word line.
 4. Theerror detection method according to claim 1, further comprises thefollowing step: marking the memory block to which the error word linebelongs as an error memory block, and terminating the programmingoperations of the memory cells connected to all the word lines of theerror memory block.
 5. The error detection method according to claim 4,further comprises the following step: reading a programmed data in thememory cells of the error memory block, and writing the programmed datainto a plurality of memory cells of another memory block.
 6. An errordetection method for a memory device, wherein the memory devicecomprises a plurality of memory blocks, and each of the memory blockshas a plurality of word lines connected to a plurality of memory cells,the error detection method comprises the following steps: performing aplurality of times of programming operations on the memory cellsconnected to each of the word lines to program the memory cells as aplurality of programming-level states; performing a plurality of timesof verifying operations on the memory cells to verify theprogramming-level states respectively; and when the amount of memorycells passing verification for one of the programming-level states isless than a lower limit amount, marking the word line as an error wordline.
 7. The error detection method according to claim 6, furthercomprises the following step: terminating the programming operations ofthe memory cells connected to the error word line.
 8. The errordetection method according to claim 7, further comprises the followingstep: reading a programmed data in the memory cells connected to theerror word line, and writing the programmed data into a plurality ofmemory cells connected to another word line.
 9. The error detectionmethod according to claim 6, further comprises the following step:marking the memory block to which the error word line belongs as anerror memory block, and terminating the programming operations of thememory cells connected to all the word lines of the error memory block.10. The error detection method according to claim 9, further comprisesthe following step: reading a programmed data in the memory cells of theerror memory block, and writing the programmed data into a plurality ofmemory cells of another memory block.
 11. An error detection method fora memory device, wherein the memory device comprises a plurality ofmemory blocks, and the memory blocks comprise at least a first memoryblock and a second memory block, the error detection method comprisesthe following steps: performing a plurality of times of programmingoperations on a plurality of memory cells of the first memory block anda plurality of memory cells of the second memory block to program thememory cells of the first memory block and the memory cells of thesecond memory block as a plurality of programming-level states;performing a plurality of times of verifying operations on the memorycells of the first memory block and the memory cells of the secondmemory block to verify the programming-level states respectively; andwhen a difference value between the number of verifications of theverifying operations for the same programming-level state of the firstmemory block and the second memory block is greater than a standardnumber, marking the first memory block and/or the second memory block aserror memory block(s).
 12. The error detection method according to claim11, wherein, marking one of the first memory block and the second memoryblock which as the larger number of verifications as an error memoryblock.
 13. The error detection method according to claim 11, wherein,marking both the first memory block and the second memory block as errormemory blocks.
 14. The error detection method according to claim 11,further comprises the following step: terminating the programmingoperations of the memory cells of the error memory block.
 15. The errordetection method according to claim 14, further comprises the followingstep: reading a programmed data in the memory cells of the error memoryblock, and writing the programmed data into a plurality of memory cellsof another memory block.